The primary goal of this research project is to develop a continuous in vitro culture system for a human malaria parasite, Plasmodium vivax, which currently cannot be maintained in vitro for an extended period of time. The resulting system will be used for culturing P. vivax parasites from human patients to conduct important biological studies of P. vivax, such as drug resistance, and development of novel antimalarial drugs and vaccines. This will help with prevention and treatment of the disease caused by the parasite in endemic areas. To accomplish this goal, we will develop a system to obtain human reticulocytes, which is essential for P. vivax growth, by directing differentiation of the hematopoetic stem cells (HSCs) isolated from human umbilical cord blood (UCB), by using recombinant cell factors and co-culture with mouse or human stromal cells. The resulting reticulocytes will be infected with Plasmodium parasites (P. falciparum and P. vivax) to test if they can support growth of the parasites. The method for cryo- preservation of the cultured reticulocytes will also be studied for distribution of the reticulocytes to research laboratories and field sites. PUBLIC HEALTH RELEVANCE: The primary goal of this research project is to develop a continuous in vitro culture system of human reticulocytes for propagating a human malaria parasite, Plasmodium vivax. Currently, this system is not available and its absence impedes the development of drugs and/or vaccines for malaria caused by this parasite. To accomplish this goal, human reticulocytes will be developed through the directed differentiation of hematopoetic stem cells (HSCs) isolated from human umbilical cord blood (UCB). The enriched human reticulocytes will be tested for infection with Plasmodium parasites. Various methods for cryo- preservation of the cultured reticulocytes will be evaluated to create a qualified, long-term supply of the new culture system.